The effect of two difunctional chain extenders, 1,6-diisocyanatohexane (NCO) and 1,4-butanediol diglycidyl ether (EPOX), in the reactive melt-processing of a post-consumer poly(ethylene terephthalate) (r-PET) was investigated. The torque evolution during processing in a batch mixer and the molecular weight of the chain-extended r-PET, as determined by SEC analysis, were comparatively evaluated. A simple mathematical model proposed here was used to fit the obtained molecular weights. Two polyfunctional chain extenders, poly(phenyl isocyanate-co-formaldehyde) (P-NCO) and a styrene-acrylate copolymer bearing epoxide groups (P-EPOX), were also used and their reactivity was compared with that of the difunctional ones by analyzing torque and melt flow rate data. The different reactivity of the two functional groups and the structure of the final polymer (either linear or branched depending on the type of chain extender) affect both crystallization behaviour and tensile properties of the modified r-PET. Fine tuning of the latter properties by suitable chain extender(s) selection and formulation is anticipated.
Chain extension and branching of poly(ethylene terephtalate) (PET) with di- and multifunctional epoxy or isocyanate additives: an experimental and modelling study
COLTELLI, MARIA BEATRICE;SAVI, STEFANIA;BIANCHI, SABRINA;
2012-01-01
Abstract
The effect of two difunctional chain extenders, 1,6-diisocyanatohexane (NCO) and 1,4-butanediol diglycidyl ether (EPOX), in the reactive melt-processing of a post-consumer poly(ethylene terephthalate) (r-PET) was investigated. The torque evolution during processing in a batch mixer and the molecular weight of the chain-extended r-PET, as determined by SEC analysis, were comparatively evaluated. A simple mathematical model proposed here was used to fit the obtained molecular weights. Two polyfunctional chain extenders, poly(phenyl isocyanate-co-formaldehyde) (P-NCO) and a styrene-acrylate copolymer bearing epoxide groups (P-EPOX), were also used and their reactivity was compared with that of the difunctional ones by analyzing torque and melt flow rate data. The different reactivity of the two functional groups and the structure of the final polymer (either linear or branched depending on the type of chain extender) affect both crystallization behaviour and tensile properties of the modified r-PET. Fine tuning of the latter properties by suitable chain extender(s) selection and formulation is anticipated.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
